Split Topic: Triple Trees

[L.A.B.]

The top tree for an 850 has forward-facing threaded lugs for the Ign, switch/idiot light panel.

Only the 850 MKIII top yoke/tree has the two front lugs. The MkIII also has a different type of steering lock.

Offset, clamp size and width are the same.

750 and 850 yokes/trees SHOULD NOT BE MIXED, they are dimensionally different, because the 750 and 850 frames have different steering geometries.


Use pairs of 'ANG' marked (underside) yokes with 850 frames.

 

[Danno]

Re: WTB: Triple Tree's

The difference in the geometries is in the steering neck itself, not the trees. The trees are dimensionally the same; Same center-to-center measurement on the tube clamps and same offset from the steering axis to the clamp centers. The yokes I have for sale are 750 with no lugs on the top yoke for the 850-type dash panel. The 850 frame has a degree or so less steep rake than the 750 (28 vs. 27).

 

[Danno]

Re: WTB: Triple Tree's

The top tree for an 850 has forward-facing threaded lugs for the Ign, switch/idiot light panel.

Only the 850 MKIII top yoke/tree has the two front lugs. The MkIII also has a different type of steering lock

The distance to the center of the steering lock hole from the center of the stem is exactly the same on both types of trees. The lock cylinder hole on the 850 top tree is about 1/2" in diameter while the hole on the 750 tree is about 3/4" Both the 750 and the 850 have 2" of steering lock-to-lock on the botom trees.

 

[Danno]

Re: WTB: Triple Tree's

750 and 850 yokes/trees SHOULD NOT BE MIXED, they are dimensionally different, because the 750 and 850 frames have different steering geometries.

Not true. Both bottom trees (750 and 850) are dimensionally identical. And how is this relevant? He is getting a PAIR (top and bottom) 750 trees with steering stem. I have both right in front of me, so you must be mistaken.

 

[L.A.B.]

I've split these posts away from a 'Wanted' ad. because it was developing into a thread and possibly warrants some further discussion as there is a difference of opinion.

 

[ML]

Danno,
Can you identify the part number stamping on both clamps? There is the mystery of the unrecorded '71 750 clamps...stamped numbers but does not show in any factory parts book.

Mick

 

[Danno]

750 bottom clamp 064083

750 top clamp 081017

850 bottom clamp 08 (the rest was wiped out by the drilling for the brake line fitting)

850 top clamp 065721

The 750 bottom clamp and the 850 top clamp are both stamped ANG

P.S. I know they have not ben mixed because the 750 clamps are painted with silver Imron and both have chips and nicks. The 850 clamps still have the stock silver/aluminum paint.

 

[L.A.B.]

Re: WTB: Triple Tree's

Both bottom trees (750 and 850) are dimensionally identical.

Quoted from the 1973 750/850 parts list:

"061916 Lower yoke 750 only
064078 Lower Yoke 850 Only

061915 Upper Yoke with stem 750 Only
064080 Upper Yoke with stem 850 Only"

 

[Danno]

As stated in the other thread, there ARE differences: The 850 top clamp has the lugs for the ignition switch/idiot light panel. The holes for the fork locks, while on the same centers, are different diameters. The 850 lower clamp is drilled and milled for the brake line fitting pass-through. Width leg-to-leg, offset, and tube sizes are identical

 

[L.A.B.]

Can you identify the part number stamping on both clamps? There is the mystery of the unrecorded '71 750 clamps...stamped numbers but does not show in any factory parts book.

I don't think any of the numbers be found on the underside of the yokes are "stamped", but are in fact "cast-in" therefore they are not part numbers.

 

[Danno]

This topic should be labeled "Split Hairs" I was incorrect-the numbers are cast in. Are you happy yet?

 

[ML]

The '71 Commando has a top clamp "cast number" (sorry for saying stamp) as 061917. I have one staring at me. And a '70 and a '73 and a '74. That p/n is not recorded in any factory parts book. It was soon replaced by 061915. There is a previous thread on this topic covering much of the circumstances of why the 71 frame was deemed to be unstable particulary at higher speed. In respect to long time Norton mechanics, they all say don't mix 750 and 850 steering clamps for some good reason.

Mick

 

[L.A.B.]

As stated in the other thread, there ARE differences: The 850 top clamp has the lugs for the ignition switch/idiot light panel.

ONLY the 850 MkIII 066649 top yoke has the front lugs, as only the MkIII had the switch panel.

750 bottom clamp 064083

The 750 bottom clamp and the 850 top clamp are both stamped ANG

As far as I'm aware the "ANG 064083" casting number is an 850 part?

 

[Danno]

If that's true, it shoots a hole in your theory that the clamps can't be mixed. I have ANG on one clamp on the bike and ANG on the other in a box. My bike (titled as '71) was originally restored and updated with MkIII power train and running gear in 1984 and ridden until 1994 when it was put in storage.

 

[Danno]

As stated in the other thread, there ARE differences: The 850 top clamp has the lugs for the ignition switch/idiot light panel.

ONLY the 850 MkIII 066649 top yoke has the front lugs, as only the MkIII had the switch panel.

Again, splitting hairs. I was referring to the 850 clamp I am looking at. I don't have an 850 Mk II or I (was there such an animal?) triple clamp pair to refer to.

 

[norbsa48503]

It is not part # until it’s machined. The casting #'s are always at least one # off the part #. So I.E. 06-5445 would then become after machining the part found in the book 06-5446 these are just made up #'s but you get the idea.

 

[Danno]

The '71 Commando has a top clamp "cast number" (sorry for saying stamp) as 061917. I have one staring at me. And a '70 and a '73 and a '74. That p/n is not recorded in any factory parts book. It was soon replaced by 061915. There is a previous thread on this topic covering much of the circumstances of why the 71 frame was deemed to be unstable particulary at higher speed. In respect to long time Norton mechanics, they all say don't mix 750 and 850 steering clamps for some good reason.

Mick

The first number may be what I have. The number is obscured by a hole drilled in the clamp. I have a lot of mixed parts on my bike. If there were an issue, I would have encountered it long before now. When I converted the trans back to right-side shift, a guy told me I couldn't use a certain inner cover as it was for an earlier model. It's still there, functioning perfectly. I tend to take anything I hear with a grain of salt, but I fully believe in the things I've done and gotten away with despite finger-wagging and knowing nods.

 

[L.A.B.]

If that's true, it shoots a hole in your theory that the clamps can't be mixed.

Well, it isn't MY theory! This has been known about for years and the subject has certainly been dicussed a number of times before on the forum?

If they are supposedly the same parts, then why are the 750/850 upper and lower yoke part numbers different?

"061916 Lower yoke 750 only
064078 Lower Yoke 850 Only

061915 Upper Yoke with stem 750 Only
064080 Upper Yoke with stem 850 Only"

 

[Danno]

Sorry. You brought it up and gave it the blessing of conventional wisdom. These are, after all, machines with a lot of commonality of parts and from an era when CNC machines and real-time prototyping didn't exist. This discussion is akin to an argument on whether different handles can be used on a certain axehead. They're old motorcycles, fergawedsakes, not moon rockets.

 

[Hortons Norton]

I think they are just trying to help, It was well know in the 70's that mixing them caused instability at high speeds. But your right, They will fit and you can use them if you want.